Display and touch screens can include multiple substrates stacked in sequence, including items such as a liquid crystal display, one or more filters to modify the light to and from the liquid crystal display and a cover glass or lens to provide protection to display components and provide a user with a finished surface. In many cases one or more of these substrates are bonded together using liquid optically clear adhesives (LOCAs). The use of LOCA has become popular in the manufacture of the current generation of display applications in part because, compared to adhesive tape, LOCA is easier to rework and has good gap filling capability.
Since LOCAs are in liquid form, they can require special care when applying them to substrates. In particular, care should be taken to ensure that the introduction of bubbles or voids between the substrates is avoided. In addition, care should be taken to avoid inconsistent curing of the LOCA in different locations of the substrates so as to prevent distortions and visible defects. Consistent process parameters related to LOCA applications can be difficult to control in a manufacturing setting. Inconsistent process parameters can lead to high part rejection rates or defects in the visual quality of the final product.